OBJECTIVES: 1. To determine as accurately as possible by X-ray crystallography the three-dimensional structure of the thermostable protease thermolysin and to relate the structure to the biological function of the enzyme. 2. To continue the study of the structure of T4 phage lysozyme and to examine the factors influencing the structure, function and stability of proteins by comparing of a variety of mutant enzymes. 3. To continue the structural analysis of a bacteriochlorophyll-protein complex which is expected to give unique insights into chlorophyll-packing and chlorophyll-protein interactions in a photosynthetic complex. 4. To solve the structure of a serine protease from the loose connective tissue of the rat.